This is the intended use of the radio.
Car: This means that the radio is for use in a vehicle. These radios usually come with mounting and installation accessories for vehicles. Please verify with the product's description for more detailed information.
Marine: This means that the radio is intended for use on the boat or for marine applications. This means that he radio itself is typically treated for marine environments and includes marine accessories. Please see the product description for more information.
Portable: These radios are intended for use on the go and can be carried in your hand. Some portable radios can be used in other applications, such as on a boat or in a car.